Simon,
This is a great tool. Your GIF animation is a great addition to PDN. I know this would require more of a user interface and since I haven't done any plug-in development, I don't know what would be involved or if it's even possible given the hooks available.
Instead of exporting each layer as a frame in the animation, it would be nice to add an animation editor that would allow one to manage the frames independent of the layers. The idea would be that I would add a frame (and the length that frame is displayed) and I can modify what layers are part of that frame. When I select a frame in the animation list, I can then show/hide layers that are associated with that animation frame. That gives us a lot more flexibility when creating animation sequences since many frames would share the same content of a layer. If you go this far, it would be also nice to have the ability to change the time of each frame individually verses all sharing the same time.
I've mocked up an animation window just for reference here:
It uses the same interface we are all familiar with with layers.
I am sure there are plenty of plug-in developers that can help. At some point my skills will get to a level where I can contribute as well, although that will likely be a while!
Thanks again for a great contribution.
--Ed